ABSTRACT
From the point of view of oxidation catalysis, of great importance is the presence on the surface of the oxides of redox centers, which may accept or donate odd electrons. This problem was already tackled in Chapter 2, where the possible role of 0 2-surface ions as one-electron-donor centers was discussed. The same function can also be fulfilled by metal atoms in low oxidation state, e. g., by C0 2+ ions in CoO or Ni2+ in NiO. On the other hand, metal atoms in high valence state, e.g., VV in V205, are electron acceptors or, in other words, oxidation centers. Redox centers are frequently connected with the presence of lattice defects in the surface or in the near-to-the-surface layer of the oxides.
